Moisture Removal and Condensation and Humidity Management Apparatus for a Breathing Circuit

ABSTRACT

A moisture removal and condensation and humidity management apparatus for a breathing circuit comprises a breathing circuit tubing defining a breathing gas conduit. The breathing gas has a first humidity level and a level of moisture therein. A dry gas conduit is adjacent at least a portion of the breathing gas conduit. The dry gas flow is configured to have a second humidity level lower than the first humidity level. A moisture transmission pathway is provided between the breathing gas conduit and the dry gas conduit, such that humidity in the flow of breathing gas is lowered and moisture is transferred to the dry gas flow. The moisture transmission pathway may be provided by a permeable portion which is permeable to water vapor but impermeable to liquid water, or by one or more perforations which permit drainage of liquid water from the breathing gas conduit to the dry gas conduit.

CROSS REFERENCE TO RELATED APPLICATION

This application is a Continuation of U.S. patent application Ser. No.15/099,051 filed Apr. 14, 2016, which claims the benefit of U.S.Provisional Application No. 62/148,077 filed Apr. 15, 2015, thedisclosures of which are hereby incorporated by reference in theirentireties.

FIELD OF THE INVENTION

The present invention relates generally to a medical device. Moreparticularly, the present invention is related to a moisture removal andcondensation and humidity management apparatus for placement with abreathing circuit.

BACKGROUND

A breathing circuit delivers medical gas to a patient under pressure ina prescribed volume and breathing rate. The medical gas is oftenhumidified by a humidifier located at or near the ventilator orrespirator. The optimum respiratory circuit delivers 100% RH medicalgases to the patient while reducing the amount of humidity andsubsequent condensate delivered back to the ventilator through theexpiratory limb. Therefore, the humidified gas has to travel through allor most of the tubing and has time to cool. Cooling of the gas leads torainout or condensation in the breathing tube and collection of waterwithin the breathing circuit.

Several possible solutions to the problem of rainout have beendeveloped. One such proposed solution is a heating wire provided alongthe length of the tube. The wire may be provided within the interior ofthe tubing or alternatively may be embedded along the interior of thetubing. The wire heats the humidified gas traveling through the tubingto prevent the gas from cooling, thus preventing the problem of watercondensing out of the gas traveling through the breathing circuit.However, the manufacture of such heated wire respiratory circuits can betime consuming and costly.

Another possible solution, which eliminates the heated wire, is toprovide a water collection device somewhere within the breathingcircuit. A water collection apparatus is typically placed in theexpiratory limb of the respiratory circuit to collect and allow formanual removal of excessive condensation prior to the gases entering theventilator or respirator. It is known that excessive condensate enteringa ventilator or respirator from the expiratory limb of a respiratorycircuit can harm the device.

Most frequently, the water collection device is designed to trap thecondensed water vapor in a removable container. When the container isremoved, a valve can be actuated to create a gas tight seal for thebreathing circuit. However, this type of water collection device has tobe monitored and manually emptied, causing risk of patient or caregiverinfection. The removal of moisture and condensation management is notautomatic. Furthermore, the removable container is often only at onediscrete point along the breathing circuit, and may need to be loweredto gravitationally collect liquid, which may be impractical.

Another possible solution is to provide a permeable membrane in thebreathing circuit tubing which is permeable to water vapor butimpermeable to liquid water, such that moisture inside the breathing gasflow inside such tubing dissipates to outside the tubing via such amembrane, and out to the ambient air surrounding the tubing. The problemwith this solution is at least two-fold: first, such a thin walledmembrane which is exposed to the surroundings can be easily punctured ordamaged; and second, due to a relatively high humidity in the ambientconditions, there can be a limited humidity differential between thebreathing gas flow and the ambient surroundings, so that the capacityfor moisture to dissipate passively through the permeable membrane toambient surroundings can also be limited.

Accordingly, it is desirable to provide an improved apparatus forremoving or decreasing water vapor, moisture, or condensate in abreathing circuit. It is further desirable that the improved apparatusfor removing water vapor, moisture or condensate from the breathingtube, eliminates the need to monitor the device or to heat theexhalation limb of the breathing tube, and is not dependent on thepositioning of the device, protects the device and its moisture andhumidity transmission mechanism from damage, and increases its capacityfor moisture removal and condensation management in a breathing circuit.

SUMMARY OF THE INVENTION

The foregoing needs are met, to a great extent, by the presentinvention, wherein a moisture removal and condensation and humiditymanagement apparatus for a breathing circuit arranged between a patientand a ventilator is provided, comprising a breathing circuit tubingdefining a breathing gas conduit for a flow of breathing gas therein,the breathing gas having a first humidity level and a level of moistureor condensate therein. A dry gas conduit is disposed adjacent at least aportion of the breathing gas conduit for a dry gas flow in said dry gasconduit, the dry gas flow being configured to have a second humiditylevel lower than the first humidity level. A moisture transmissionpathway is included between the breathing gas conduit and the dry gasconduit, such that humidity in the flow of breathing gas is lowered andmoisture or condensate in the flow of breathing gas is transferred tothe dry gas flow. The dry gas conduit is closed to ambient air aroundthe apparatus

In one embodiment of the present invention, the breathing circuit tubingcomprises a permeable portion which is permeable to water vapor butimpermeable to liquid water, such that the moisture transmission pathwayis provided by such permeable portion of the breathing circuit tubing.

In another embodiment of the present invention, the breathing circuittubing is formed by an inner tube defining the breathing gas conduit,and the dry gas conduit is formed by an outer tube surrounding the innertube, the dry gas conduit being defined by an annular flow conduitdefined between the inner tube and outer tube.

In another embodiment of the present invention, the breathing circuittubing is formed by an inner tube defining the breathing gas conduit,and the dry gas conduit is formed by an outer tube surrounding the innertube, an annular space being defined between the inner tube and outertube. Furthermore, a dividing wall is formed between the inner tube andouter tube in the annular space to divide the dry gas conduit into afirst, delivery conduit for flow of dry gas from a first end of theapparatus to a second end of the apparatus, and a second, return conduitfor flow of dry gas from the second end of the apparatus to the firstend of the apparatus.

In another embodiment of the present invention, the permeable portion ofthe breathing circuit tubing is a permeable membrane which forms aportion of said breathing circuit tubing.

In another embodiment of the present invention, the breathing circuittubing comprises one or more perforations which permit drainage ofliquid water from the breathing gas conduit to the dry gas conduit, suchthat the moisture transmission pathway is provided by such one or moreperforations of the breathing circuit tubing.

In another embodiment of the present invention, the breathing circuitconduit and dry gas conduit share a common dividing wall, the commondividing wall having the moisture transmission pathway.

In another embodiment of the present invention, the common dividing wallcomprises a permeable portion which is permeable to water vapor butimpermeable to liquid water, such that the moisture transmission pathwayis provided by such permeable portion of the common dividing wall.

In another embodiment of the present invention, the permeable portion ofthe breathing circuit tubing is a permeable membrane which forms aportion of said common dividing wall.

In another embodiment of the present invention, the common dividing wallcomprises one or more perforations which permit drainage of liquid waterfrom the breathing gas conduit to the dry gas conduit, such that themoisture transmission pathway is provided by such one or moreperforations of the common dividing wall.

In another embodiment of the present invention, an exit port is providedon the apparatus for the dry gas conduit having a filter, the dry gasexiting via the exit port to the ambient environment surrounding theapparatus.

In another embodiment of the present invention, an input port isprovided on the apparatus for the dry gas conduit having a flow orvolumetric control element for the dry gas flow.

In another embodiment of the present invention, an exit port is providedon the apparatus for the dry gas conduit which is connected to a sourceof suction.

In another aspect of the present invention, method of removing moistureor controlling condensation in a breathing circuit is provided,comprising providing an apparatus as disclosed in any of the precedingrecited embodiments of the present invention. The apparatus isconfigured and arranged to be disposed between a ventilator and apatient. Breathing gas is supplied via the breathing circuit tubing to apatient. And dry air is supplied through the dry gas conduit to removemoisture or liquid water condensate from the breathing gas conduit. Inanother embodiment, one or more of the first and second humidity levelsmay be monitored using a humidity sensor. In one or more furtherembodiments, the breathing circuit tubing is an expiratory limb of aventilator circuit.

There has thus been outlined, rather broadly, certain embodiments of theinvention in order that the detailed description thereof herein may bebetter understood, and in order that the present contribution to the artmay be better appreciated. There are additional embodiments of theinvention that will be described below and which form the subject matterof the claims appended hereto.

In this respect, before explaining at least one embodiment of theinvention in detail, it is to be understood that the invention is notlimited in its application to the details of construction and to thearrangements of the components set forth in the following description orillustrated in the drawings. The invention is capable of embodiments inaddition to those described and of being practiced and carried out invarious ways. Also, it is to be understood that the phraseology andterminology employed herein, as well as the abstract, are for thepurpose of description and should not be regarded as limiting.

As such, those skilled in the art will appreciate that the conceptionupon which this disclosure is based may readily be utilized as a basisfor the designing of other structures, methods and systems for carryingout the several purposes of the present invention. It is important,therefore, that the claims be regarded as including such equivalentconstructions insofar as they do not depart from the spirit and scope ofthe present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view illustrating an apparatus incorporated intoor as part of a breathing gas circuit in accordance with one or moreembodiments of the present invention;

FIG. 2 a schematic cross-sectional view illustrating the apparatus ofFIG. 1 in one or more embodiments of the present invention;

FIG. 3 a schematic cross-sectional view illustrating the apparatus ofFIG. 1 in one or more additional embodiments of the present invention;

FIG. 4 is a schematic cross-sectional view of an apparatus incorporatedinto or as part of a breathing gas circuit in accordance with one ormore additional embodiments of the present invention.

DETAILED DESCRIPTION

The invention will now be described with reference to the drawingfigures, in which like parts are referred to with like referencenumerals throughout. One or more embodiments in accordance with thepresent invention provide a moisture removal and condensation andhumidity management apparatus for a breathing circuit to rapidly removewater vapor or condensate from a humidified medical gas travelingthrough a breathing circuit between a ventilator and a patient or thepatient and the ventilator. As used herein, a “breathing circuit” or“breathing gas circuit” is any arrangement of tubing or conduits whichcarries gases to be administered to and from a patient, such as from aventilator, and which may include additional accessories or devicesattached to it. Such “breathing gases” may include oxygen, air or anycomponent thereof, and are configured for absorbing high levels ofmoisture and/or being humidified prior to administration to a patient,or during administration to a patient, suitable for medicalapplications.

FIG. 1 is a schematic view illustrating an apparatus incorporated intoor as part of a breathing gas circuit in accordance with one or moreembodiments of the present invention. A moisture removal andcondensation and humidity management apparatus 10 for a breathingcircuit includes a section or length of breathing circuit tubing 11defining a breathing gas conduit 12 for a flow (B) of breathing gastherein. The breathing gas flows from a first, upstream end 10A of thedevice 10, through the conduit 12 defined within device 10, to a second,downstream end 10B of the device 10. The breathing gas is configured tohave a first humidity level and a level of moisture therein, which maybe calibrated based on the needs of the patient. In one embodiment sucha length of breathing circuit tubing 11 may be in an expiratory limb ofa breathing circuit, such as, for example, somewhere between a patientand a ventilator. In the device 10, a dry gas conduit 14 is definedadjacent at least a portion of the breathing gas conduit 12 between thefirst end 10A and second end 10B, for a dry gas flow (D) therein. Thedry gas flow (D) is configured to have a second humidity level which islower than the first humidity level within the breathing gas conduit(B). A dry gas flow is coupled from a dry gas source (not shown) to oneor more input ports 40 which feed the dry gas flow (D) into the dry gasconduit 14, which then flows substantially parallel to, or around thebreathing gas conduit 12.

FIG. 2 a schematic cross-sectional view illustrating the apparatus ofFIG. 1 in one or more embodiments of the present invention. As shown inFIG. 2 , the dry gas conduit 14 may be an annular flow space which isconcentric with breathing gas conduit 12. In the embodiment shown inFIG. 2 , the breathing circuit tubing 11 may be formed by an inner tube20 defining the breathing gas conduit 12, and the dry gas conduit 14 isformed by an outer sleeve or tube 22 surrounding the inner tube 20, thedry gas conduit 14 thereby being defined as an annular flow conduit 24defined between the inner tube 20 and outer tube 22. One, or both, ofthe inner and outer conduits may be formed by corrugated tubing.Alternatively, the inner tube 20 could define the dry gas conduit 14 andthe annular space 24 between the inner and outer tubes 20, 22 could bethe breathing gas conduit 12. In the present invention, a sufficientstretch of surface area is shared along the breathing circuit tubing 11between the breathing gas conduit 12 and dry gas conduit 14 such that amoisture and humidity transmission pathway is enabled between the twoconduits, as further described below.

The present invention provides one or more embodiments which provide amoisture transmission pathway between the breathing gas conduit 12 andthe dry gas conduit 14, such that humidity in the flow of breathing gas(B) is lowered and moisture in the flow of breathing gas (B) istransferred to the dry gas flow (D). In FIG. 2 , such a moisturetransmission pathway (T) occurs between the higher humidity breathinggases in conduit 12 and the lower humidity dry gas flow in conduit 14. Auser can increase or decrease the level of dry gas supplied to thecircuit to manage or remove the condensate which may be transmitted fromthe breathing gas (B) to the dry gas conduit. The moisture level thusmay be reduced from within the breathing gas flow and transferred to thedry gas flow. In one or more embodiments, such as shown in FIG. 2 , thebreathing circuit tubing 11 comprises a permeable portion (not shown)along part or all of the inner conduit 20 is provided, which ispermeable to water vapor but impermeable to liquid water, such that themoisture transmission pathway (T) is provided by such permeable portionof the breathing circuit tubing. The materials comprising the permeableportion are water vapor breathable and allow passage of water vapor, asis well known to those of ordinary skill in the art. The permeableportion may form some or all of the walls of the breathing gas conduit12, such as inner tube 20, and may include a single, or composite outer,layer of water vapor breathable medium. In one embodiment, an additionalwicking layer may be added to the permeable portion. In the embodimentshown in FIG. 2 , the additional wicking layer may be disposed as aninner layer of inner conduit 20, configured to be in contact withbreathing gas flow (B) inside said conduit. Such a wicking layer may bemade of wicking material which allows for adsorption and/or absorptionof both moisture and water in any phase, gas or liquid, using acapillary action, while the outer layer of water vapor breathable mediumpermits the passage of water vapor only and not liquid water.

Examples of wicking material in the inner layer are a knit or non-wovencloth or fabric, and can be synthetic and made of polyester, polyesterand polypropylene blends, nylon, polyethylene or paper, and can bemicrofilaments or microfiber material such as Evolon® brand fabricmaterial made by Freudenberg & Co. KG. A particular example of wickingmaterial would be a non-woven material of 70% polypropylene and 30%polyester. Another example of the wicking material can be Evolon® brandfabric material having a weight of 60 or 80 grams per square meter.Examples of the outer layer of water vapor breathable medium areSympatex® brand water vapor permeable membranes made of polymers made bySympatex Technologies, including monolithic hydrophilic polyester estermembrane, including, as one example, a 12 micron thick membrane.

In another embodiment of the present invention, the breathing circuittubing 11 comprises one or more small openings or perforations (notshown) in inner tube 20 which permit drainage of liquid water from thebreathing gas conduit 12 to the dry gas conduit 14, such that another,different, moisture transmission pathway T1 is provided by such one ormore perforations between the breathing gas flow (B) and dry gas flow(D), such as shown in FIG. 2 .

FIG. 3 a schematic cross-sectional view illustrating the apparatus ofFIG. 1 in one or more additional embodiments of the present invention.In FIG. 3 , a dividing wall 30 is formed between the inner tube 20 andouter tube 22 in the annular space between said tubes to divide the drygas conduit into a first, delivery conduit 32 for flow of dry gas (D1)from a first end of the apparatus 10 to a second end of the apparatus,and a second, return conduit 34 for flow of dry gas (D2) from the secondend of the apparatus to the first end of the apparatus 10. In this way,the dry gas flow may be re-used, such as, for example, in a closed loopsystem. One or more moisture transmission pathways may be definedbetween breathing gas flow conduit (B) and one or both of dry gasconduits (D1, D2), including a permeable membrane incorporated intoinner tube 20 as described herein, or a series of perforations in theinner tube 20, as also described herein. The permeable membrane ispermeable to water vapor but impermeable to liquid water and may includeone or more layers, including a wicking layer, as described above.

FIG. 4 is a schematic cross-sectional view of an apparatus 100incorporated into or as part of a breathing gas circuit in accordancewith one or more additional embodiments of the present invention. InFIG. 4 , a breathing circuit tubing 101 defines a breathing gas conduit112 for a flow of breathing gas flow (B) therein, said breathing gashaving a first humidity level and a level of moisture therein, and a drygas conduit 114 is formed adjacent at least a portion of the breathinggas conduit 112 for a dry gas flow (D) therein, said dry gas flowconfigured to have a second humidity level lower than the first humiditylevel. In FIG. 4 , a moisture transmission pathway (T2) is providedbetween the breathing gas conduit 112 and the dry gas conduit 114, suchthat humidity in the flow of breathing gas (B) is lowered and moisturein the flow of breathing gas (B) is transferred to the dry gas flow (D).In FIG. 4 , the breathing gas conduit 112 and dry gas conduit 114 sharea common dividing wall 130, the common dividing wall 130 having themoisture transmission pathway (T2), which may be provided by a permeablemembrane incorporated into part or all of the dividing wall 130, asdescribed herein, or a series of perforations in part or all of thedividing wall 130, as also described herein. The permeable membrane ispermeable to water vapor but impermeable to liquid water and may includeone or more layers, including a wicking layer, as described above.

In one or more embodiments of the present invention, the dry gas conduit14, 32, 34, 114 can be closed to ambient air around the apparatus. Thedry gas conduit therefore can be configured to provide a stream of drygas flow at humidity levels which are significantly lower than thehumidity in the breathing gas conduit 12, 112. An exit port for the drygas conduit may further include a filter, the dry gas exiting via theexit port to the ambient environment surrounding the apparatus. Such anexit port may also be connected to a source of suction. An input portfor the dry gas conduit may include a flow or volumetric control elementfor the dry gas flow.

The present invention therefore uses the differential between humidityor moisture content between the respective flows in the breathing gasconduit 12, 112, vs. the dry gas conduit 14, 32, 34, 114, which allowsfor greater extraction or diffusion of moisture and humidity from thebreathing gas flow to the dry gas flow, which is further assisted by theconvective action of the dry gas flow along the common surface areashared between the breathing gas conduit 12, 112, and the dry gasconduit 14, 32, 34, 114, such as along inner conduit 20, or commondividing wall 130.

The present invention therefore provides a superior way of removal ofmoisture or water vapor from a breathing circuit, which is better thanwater traps or other fluid dissipation or moisture removal devices knownin the prior art. The result of the inventive apparatus disclosed isthat when the apparatus is coupled with a breathing circuit, rainout orcondensation in the breathing tube and collection of water within thebreathing circuit is significantly reduced. The present inventiontherefore allows for removal of the collected condensate on the innerwalls of a breathing gas conduit, which is then transported away throughan outer sleeve which provides the dry gas conduit. The outer tube ofthe apparatus can also serve to protect the inner tube from damage orpuncture, which can be especially vulnerable to damage or puncture whenit incorporates a permeable membrane and/or perforations as describedherein. To provide additional strength and puncture protection, anadditional outer cover structure can be added to the apparatus. Thepresent invention therefore represents an improvement over the knownprior art by providing the benefits of: (a) reducing or eliminating usermanagement of condensate levels within a breathing circuit, and/or (b)reducing the humidity output from an expiratory limb of a breathingcircuit to reduce the collection of condensate which may be collected inthe ventilator.

The many features and advantages of the invention are apparent from thedetailed specification, and thus, it is intended by the appended claimsto cover all such features and advantages of the invention which fallwithin the true spirit and scope of the invention. Further, sincenumerous modifications and variations will readily occur to thoseskilled in the art, it is not desired to limit the invention to theexact construction and operation illustrated and described, andaccordingly, all suitable modifications and equivalents may be resortedto, falling within the scope of the invention.

1. A moisture removal apparatus comprising: a first tube; a second tube,the first tube and the second tube defining: a breathing gas conduitthat directs a flow of breathing gas in a direction from an upstream endof the apparatus to a downstream end of the apparatus; and a dry gasconduit that directs a dry gas flow in the direction from the upstreamend of the apparatus to the downstream end of the apparatus; and amoisture transmission pathway between the breathing gas conduit and thedry gas conduit that lowers the humidity of the breathing gas bytransferring the humidity to the dry gas flow.
 2. The moisture removalapparatus of claim 1, wherein the moisture transmission pathway ispermeable to water vapor but impermeable to liquid water.
 3. Themoisture removal apparatus of claim 1, wherein the first tube is aninner tube and the second tube is an outer tube that is concentric withthe inner tube.
 4. The moisture removal apparatus of claim 3, whereinthe inner tube defines the breathing gas conduit, and further comprisingan annular space between the inner tube and the outer tube, the annularspace defining the dry gas conduit.
 5. The moisture removal apparatus ofclaim 1, wherein at least one of the first tube or the second tube is acorrugated tube.
 6. The moisture removal apparatus of claim 3, whereinthe inner tube includes a permeable portion that defines the moisturetransmission pathway that is permeable to water vapor but impermeable toliquid water.
 7. The moisture removal apparatus of claim 6, wherein thepermeable portion spans the entire wall of the inner tube.
 8. Themoisture removal apparatus of claim 6, wherein the permeable portionincludes a hydrophilic polyester ester membrane.
 9. The moisture removalapparatus of claim 1, further comprising: an exit port fluidly coupledto the dry gas conduit; and a filter fluidly coupled to the exit port.10. The moisture removal apparatus of claim 1, wherein the apparatus isconfigured to be an expiratory limb of a ventilator circuit.
 11. Themoisture removal apparatus of claim 1, wherein the dry gas conduit is afirst dry gas conduit, the dry gas flow is a first dry gas flow, thedirection is a first direction, and further comprising: a return conduitthat directs a second dry gas flow in a second direction from thedownstream end to the upstream end of the apparatus.
 12. A moistureremoval apparatus comprising: an inner tube defining a breathing gasconduit that directs a flow of breathing gas, the inner tube including apermeable portion that defines a moisture transmission pathway that ispermeable to water vapor; an outer tube concentric with the inner tube;an annular space between the inner tube and the outer tube, the annularspace defining a first dry gas conduit that directs a first dry gas flowin a first direction from a first end of the apparatus to a second endof the apparatus; and a return conduit that directs a second dry gasflow in a second direction from the second end of the apparatus to thefirst end of the apparatus.
 13. The moisture removal apparatus of claim12, wherein the return conduit is positioned within the annular space.14. The moisture removal apparatus of claim 13, further comprising adividing wall between the inner tube and the outer tube that divides theannular space into the first dry gas conduit and the return conduit. 15.The moisture removal apparatus of claim 12, wherein the outer tube is acorrugated tube; and wherein the moisture transmission pathway isimpermeable to liquid water.
 16. The moisture removal apparatus of claim12, wherein the apparatus is configured to be an expiratory limb of aventilator circuit.
 17. A moisture removal apparatus comprising: abreathing circuit tube including: a breathing gas conduit that directs aflow of breathing gas in a first direction from a first end of theapparatus to a second end of the apparatus; and a dry gas conduit thatdirects a first dry gas flow in the first direction; and a moisturetransmission pathway between the breathing gas conduit and the dry gasconduit that lowers the humidity of the breathing gas by transferringthe humidity to the first dry gas flow; and wherein the moisture removalapparatus includes at least one of: a return conduit that directs asecond dry gas flow in a second direction from the second end of theapparatus to the first end of the apparatus; or a dividing wall thatdivides the breathing circuit tube into the breathing gas conduit andthe dry gas conduit, the dividing wall including a permeable portionthat defines the moisture transmission pathway, the moisturetransmission pathway being permeable to water vapor.
 18. The moistureremoval apparatus of claim 17, wherein the breathing circuit tube is acorrugated tube.
 19. The moisture removal apparatus of claim 17, whereinthe moisture transmission pathway is impermeable to liquid water. 20.The moisture removal apparatus of claim 17, wherein the moisture removalapparatus includes the return conduit that directs the second dry gasflow in the second direction from the second end of the apparatus to thefirst end of the apparatus; and further comprising: an inner tube thatdefines the breathing gas conduit; and an outer tube concentric with theinner tube, the inner tube and outer tube defining an annular spacebetween the inner tube and the outer tube, the annular space definingthe breathing gas conduit; and wherein the return conduit is positionedwithin the annular space.